Fixes emagged deep fryer softlocks (#18874)

code/modules/food_and_drinks/kitchen_machinery/cooker.dm

@@ -136,7 +136,12 @@
 			else
 				L.death()
 		break
-	sleep(cooktime)
+	addtimer(CALLBACK(src, .proc/finish_cook, I, user), cooktime)
+
+/obj/machinery/cooker/proc/finish_cook(obj/item/I, mob/user, params)
+	if(QDELETED(I)) //For situations where the item being cooked gets deleted mid-cook (primed grenades)
+		turnoff()
+		return
 	if(I && I.loc == src)
 		//New interaction to allow special foods to be made/cooked via deepfryer without removing original functionality
 		//Define the foods/results on the specific machine		--FalseIncarnate